diff --git a/SimPEG/EM/FDEM/SrcFDEM.py b/SimPEG/EM/FDEM/SrcFDEM.py
index 6193b2f4..f524a5f2 100644
--- a/SimPEG/EM/FDEM/SrcFDEM.py
+++ b/SimPEG/EM/FDEM/SrcFDEM.py
@@ -539,10 +539,9 @@ class CircularLoop(BaseSrc):
             if not prob.mesh.isSymmetric:
                 # TODO ?
                 raise NotImplementedError('Non-symmetric cyl mesh not implemented yet!')
-            a = MagneticDipoleVectorPotential(self.loc, gridY, 'y', moment=self.radius, mu=self.mu)
-
+            a = MagneticLoopVectorPotential(self.loc, gridY, 'y', self.radius, mu=self.mu)
         else:
-            srcfct = MagneticDipoleVectorPotential
+            srcfct = MagneticLoopVectorPotential
             ax = srcfct(self.loc, gridX, 'x', self.radius, mu=self.mu)
             ay = srcfct(self.loc, gridY, 'y', self.radius, mu=self.mu)
             az = srcfct(self.loc, gridZ, 'z', self.radius, mu=self.mu)
diff --git a/SimPEG/EM/TDEM/SurveyTDEM.py b/SimPEG/EM/TDEM/SurveyTDEM.py
index 3d2c20db..ba085bf9 100644
--- a/SimPEG/EM/TDEM/SurveyTDEM.py
+++ b/SimPEG/EM/TDEM/SurveyTDEM.py
@@ -85,6 +85,9 @@ class BaseWaveform(object):
     def eval(self, time):
         raise NotImplementedError 
 
+    def evalDeriv(self, time):
+        raise NotImplementedError # needed for E-formulation 
+
 
 class StepOffWaveform(BaseWaveform):
 
@@ -95,12 +98,30 @@ class StepOffWaveform(BaseWaveform):
         return 0.
 
 
+class RawWaveform(BaseWaveform):
+
+    def __init__(self, offTime=0.):
+        BaseWaveform.__init__(self, offTime, hasInitialFields=True)
+
+    def eval(self, time):
+        raise NotImplementedError 'RawWaveform has not been implemented, you should write it!'
+
+
+class TriangularWaveform(BaseWaveform):
+
+    def __init__(self, offTime=0.):
+        BaseWaveform.__init__(self, offTime, hasInitialFields=True)
+
+    def eval(self, time):
+        raise NotImplementedError 'TriangularWaveform has not been implemented, you should write it!'
+
+
 
 class BaseSrc(SimPEG.Survey.BaseSrc):
 
     rxPair = Rx
     integrate = True
-    waveformPair = BaseWaveform
+    waveformPair = StepOffWaveform
 
     @property
     def waveform(self):
@@ -141,6 +162,12 @@ class BaseSrc(SimPEG.Survey.BaseSrc):
     def S_e(self, prob, time):
         return Zero()
 
+    def S_mDeriv(self, prob, time):
+        raise NotImplementedError
+
+    def S_eDeriv(self, prob, time):
+        raise NotImplementedError
+
 
 class MagDipole(BaseSrc):
     def __init__(self, rxList, waveform=None, loc=None, orientation='Z', moment=1., mu=mu_0):  
diff --git a/SimPEG/EM/TDEM/TDEM.py b/SimPEG/EM/TDEM/TDEM.py
index c9b627ae..192fa692 100644
--- a/SimPEG/EM/TDEM/TDEM.py
+++ b/SimPEG/EM/TDEM/TDEM.py
@@ -267,7 +267,7 @@ class Problem_b(BaseTDEMProblem):
             return MfMui.T * rhs
         return rhs
 
-    def getRHSDeriv(self, tInd, src, v, adjoint=False):
+    def getRHSDeriv(self, tInd, src, v, dbn_dm_v, adjoint=False):
 
         dt = self.timeSteps[tInd]
         C = self.mesh.edgeCurl