Article 38.05 of the Texas Code of Criminal Procedure forbids a trial judge from commenting on the weight of evidence or conveying an opinion of the case to the jury. See TEX. CODE CRIM. PROC. ANN. art. 38.05 (Vernon 1979). Rule 105(a) of the Texas Rules of Criminal Evidence provided that when evidence is admissible for one purpose and not admissible for another purpose, the court must restrict the evidence to its proper scope and instruct the jury accordingly if requested to do so. See TEX. R. CRIM. EVID. 105(a) (now TEX. R. EVID. 105(a)). The party opposing the admission of evidence has the burden of requesting the correct limiting instruction. See Plante v. State, 692 S.W.2d 487, 493 (Tex. Crim. App. 1985).